glass block

Acrylic block combines the beauty of glass block with a
tough scratch-resistant acrylic plastic, making it considerably lighter than
glass block. It is available in prefabricated window and door panels that are
fully glazed. These acrylic block assemblies are held together by resilient
polymer clips and encased in aluminum or vinyl frames. The window and door panels
are easy to install with standard tools, and because acrylic block is installed
without mortar, there’s no mess and fewer headaches. The blocks are available
in three finishes: clear, patterned, and frosted. They come in standard 6-inch
and 8-inch square sizes and 2- and 3-inch thicknesses. The block can be used
for custom windows, door inserts, wall partitions, and curved shower
enclosures.